# **IN**

## **Grammar Description**

The IN operator can specify multiple specific values in the `WHERE` statement, essentially abbreviation for multiple `OR` conditions.

## **Grammar Structure**

```sql
SELECT column1, column2, ...
FROM table_name
WHERE column_name IN (value1, value2, ...);
```

## **Example**

```text
create table t2(a int,b varchar(5),c float, d date, e datetime);
insert into t2 values(1,'a',1.001,'2022-02-08','2022-02-08 12:00:00');
insert into t2 values(2,'b',2.001,'2022-02-09','2022-02-09 12:00:00');
insert into t2 values(1,'c',3.001,'2022-02-10','2022-02-10 12:00:00');
insert into t2 values(4,'d',4.001,'2022-02-11','2022-02-11 12:00:00');

mysql> select * from t2 where a in (2,4);
+------+------+----------------------------------------------------------------------------------------------------------------
| a | b | c | d | e |
+------+------+----------------------------------------------------------------------------------------------------------------
| 2 | b | 2.001 | 2022-02-09 | 2022-02-09 12:00:00 |
| 4 | d | 4.001 | 2022-02-11 | 2022-02-11 12:00:00 |
+------+------+----------------------------------------------------------------------------------------------------------------

mysql> select * from t2 where a not in (2,4);
+------+------+----------------------------------------------------------------------------------------------------------------
| a | b | c | d | e |
+------+------+----------------------------------------------------------------------------------------------------------------
| 1 | a | 1.001 | 2022-02-08 | 2022-02-08 12:00:00 |
| 1 | c | 3.001 | 2022-02-10 | 2022-02-10 12:00:00 |
+------+------+----------------------------------------------------------------------------------------------------------------

mysql> select * from t2 where b not in ('e',"f");
+------+------+----------------------------------------------------------------------------------------------------------------
| a | b | c | d | e |
+------+------+----------------------------------------------------------------------------------------------------------------
| 1 | a | 1.001 | 2022-02-08 | 2022-02-08 12:00:00 |
| 2 | b | 2.001 | 2022-02-09 | 2022-02-09 12:00:00 |
| 1 | c | 3.001 | 2022-02-10 | 2022-02-10 12:00:00 |
| 4 | d | 4.001 | 2022-02-11 | 2022-02-11 12:00:00 |
+------+------+----------------------------------------------------------------------------------------------------------------

mysql> select * from t2 where e not in ('2022-02-09 12:00:00') and a in (4,5);
+------+------+----------------------------------------------------------------------------------------------------------------
| a | b | c | d | e |
+------+------+----------------------------------------------------------------------------------------------------------------
| 4 | d | 4.001 | 2022-02-11 | 2022-02-11 12:00:00 |
+------+------+----------------------------------------------------------------------------------------------------------------

```

## **limit**

* Currently, only constant lists are supported on the left side of `IN`.
* `IN` only supports single column data on the left, and does not support tuples composed of multiple columns.
* `IN` has not processed the `NULL` value very well, and the `NULL` value cannot be used on the right side.